Front Chain rings

Discuss light weight issues concerning road bikes & parts.
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eforce123
Posts: 115
Joined: Sun Apr 08, 2018 9:27 pm

by eforce123

I am wanting to get smaller chain rings on my dura ace 9000 group set.

I would like lighter if possible. Does this mean I go with sram rings? or is there another brand that is great quality and lightweight?

it is a 52/36 and 11/30 now I want to drop to the smallest front ring I can and run an 11-23 or 11-25 to save more weight.

I need my lowest gear to be below 1.20. My thought is to save weight and my current set up I am always in the low ring front and rarely jump to the big ring. I ride weeks without getting into that ring, so my thought was to drop that a lot smaller and use the bigger front ring all the time and only drop to the small one on big hills.

I am new to cycling so advise is welcomed

by Weenie


morganb
Posts: 668
Joined: Wed Mar 15, 2017 5:30 pm

by morganb

If you are only using your small ring I wouldn't recommend going to a smaller cassette in the back to save weight. The smallest normal ring is a 34T although Absolute Black makes an oval ring that is smaller and works with those cranks.

eforce123
Posts: 115
Joined: Sun Apr 08, 2018 9:27 pm

by eforce123

morganb wrote:
Tue Aug 07, 2018 6:10 pm
If you are only using your small ring I wouldn't recommend going to a smaller cassette in the back to save weight. The smallest normal ring is a 34T although Absolute Black makes an oval ring that is smaller and works with those cranks.
why not a smaller cassette in the back? Trying to learn and I like the way it is geared now cause I only use the small ring.

can I jump to an 11-32 cassette and front ring get a 38. This gives me slightly more top and bottom and I can take off the big ring entire and just run a single front. is this possible?

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themidge
Posts: 1196
Joined: Fri Jan 13, 2017 4:19 pm
Location: underneath sweet Scottish rain

by themidge

Well, you can get a 34t little ring from Shimano which seems to be the smallest size that will fit (even though the BCD is 110, so a 33t should be possible) and the aftermarket options I could find also have 34t as the smallest.
Same story with the big ring, 50t is the smallest I can find from Shimano (obviously) and I could only find Wolftooth making smaller than that (48t and 46t). If you aren't using your big ring much at the moment, then perhaps a smaller one could be in order.
Take note of your speed in different gears and when you switch rings and fiddle with Bike-calc or something, you should be able to work out what gears you want.

For clarification:
Little ring = inner chainring = small front chainring
Big ring = outer chainring = large front chainring

Or, as you say, 1x might be for you.

alcatraz
Posts: 2294
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Sorry but shimano rings are already pretty much the lightest you can put on a 4 bolt crank. Even if there were an option at a 5 grams less you'd be crazy to give up that nice shifting performance for such a small gain.

Going 34 small ring instead of 36 will not do much to your climbing gear. In fact it will do 34/36 = 0.9444 = 5.5%

In order to keep your lowest gear ratio it wouldn't even allow you to go 28t cassette. So forget about lowering weight while keeping a good climb ratio.

I'd keep the 30t cassette and keep my eyes open for an original 34t inner ring.. or 50/34 set. Don't expect wonders, just a bit less weight.

I hear there is an aftermarket 33t ring that will fit shimano 4 bolt cranks. Maybe worth a look.

For weight weenie drivetrain you need sram red.

eforce123
Posts: 115
Joined: Sun Apr 08, 2018 9:27 pm

by eforce123

So the chain rings on this website you can get a 32T and even a 28T. Is this for the main chainring on the front and not the secondary? Not sure the names of the front and smaller front chain ring.

https://garbaruk.com/products/chainring ... am-ai.html

Looking into sram etap now and their XG1190 stuff

hannawald
Posts: 590
Joined: Sat Dec 17, 2016 7:28 pm
Location: Czech Republic

by hannawald

if you have dura 9000 cranks you need 110 bcd 4 bolt chainrings (so those you posted are useless). you will not find much lighter than original shimano chainrings unless you go with Carbon-Ti. but they are more fragile. or you need different cranks but you will need different bottom bracket etc. probably you will find other places on bike where to save weight.

eforce123
Posts: 115
Joined: Sun Apr 08, 2018 9:27 pm

by eforce123

hannawald wrote:
Wed Aug 08, 2018 5:13 pm
if you have dura 9000 cranks you need 110 bcd 4 bolt chainrings (so those you posted are useless). you will not find much lighter than original shimano chainrings unless you go with Carbon-Ti. but they are more fragile. or you need different cranks but you will need different bottom bracket etc. probably you will find other places on bike where to save weight.
I should of been more specifc on Im trying to shave weight but with my riding I do not need a 52T front. I want to put something smaller then 36 and even 34T on the smaller front ring if possbible and change the front big ring to a 42 or 46. This way I can stay in the big ring most of the rider and only the small one for climbs. I thought this could help me drop to a 11-25 rear as well instead of my 11-30, if I can find a smaller front ring then a 34T.

I am totally fine with staying with dura ace for sure

hannawald
Posts: 590
Joined: Sat Dec 17, 2016 7:28 pm
Location: Czech Republic

by hannawald

here you probably find some info (there is discussion as well), but none of the options will be lighter than Dura..

https://www.cyclingabout.com/low-climbi ... -crankset/

look for sub compact when you google

by Weenie


alcatraz
Posts: 2294
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Your front derailleur usually can't support smaller than 46t chainrings. The mounting bracket usually doesn't allow the fd to go lower than 50t and the arch on the fd is larger than that made by the ring diameter. If you have a clamp-on fd then thats another story.

I think you probably should stay on 50/33 or 46/33. No weight saved. Why isn't much weight saved you ask? Shimano standard rings are hollow and surprisingly light compared to other stock rings. Putting non-stock smaller than 50t might even add weight because of their simpler construction. It also wouldn't look as nice. Check out 46/36 cx rings on shimano cranks to see what I mean.

Having a good gearing range is quite important for cycling. Do you really only go on flats? Descending you might need the 50x11 gear and climbing you will probably need the 34x30.

For dropping weight a dura-ace groupset is one of the last places one would look at. I'm curious to know about the rest of your bike. It must be quite amazing already.

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